A rapid COVID-19 test is useful, but too little to hit the pandemic.

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Bonnie La Fleur of the University of Arizona and Katherine Ellingson of the University of Arizona

(Conversation) Since September, the Food and Drug Administration has approved seven COVID-19 tests with results within 30 minutes, providing expectations for significant improvements in test access and efficiency across the United States. Most of these are viral proteins and can be processed on portable machines or cards.

The idea behind these rapid tests is to detect symptomatic, presymptomatic, and asymptomatic infected individuals before spreading the coronavirus. However, despite the massive distribution of these tests by federal authorities, more than 40 million of the 150 million rapid tests ordered by medical company Abbott have been included, but COVID. -19 Infections have surged in all states since early November.

This raises the question of whether the current influx of rapid tests can actually delay the spread of COVID-19.

In some targeted applications, and if people are taking other precautions, including wearing masks and social distance, rapid testing can be a valuable tool. However, the current availability and accuracy of these tests significantly limits their effectiveness in slowing the spread of the virus in the community.

Speed ​​rather than accuracy

Rapid antigen testing is an attractive option because, in addition to its speed, it is inexpensive, easy to manufacture, and, in theory, more widely available than the more commonly used gold standard PCR testing. However, there are trade-offs between these attributes. The diagnostic accuracy will be low. This is not very useful for accurate diagnosis of SARS-CoV-2 infection, but it is a good candidate for use as a screening tool.

A one-time test does not mean that a person can safely travel and interact without precautions. There is no completely accurate test, but there are real questions about the performance of the new rapid test.

Some test makers reported an accuracy of 84.0% to 97.6% in individuals tested within 5 days of developing COVID-19 symptoms. However, there is a clear gap between the reported performance of these tests and what was achieved in the real world. Anecdotally, these tests seem to miss a recent mild asymptomatic infection. In fact, rapid testing is only approved by the US Centers for Disease Control and Prevention in patients with symptomatic COVID-19. And, of course, people can get infected right after they are tested.

For rapid testing to effectively limit the spread of coronavirus, experts suggest that they need to be performed frequently. You may miss some cases, but many will be found if everyone is constantly being tested. But even frequent tests are not a panacea. This is only part of the approach that must include social distance, wearing masks, and other precautions.

When President Trump and many of his inner circles were infected with COVID-19, a highly publicized example of how rapid testing strategies failed occurred. This is probably due to a single superspreader event. Everyone reportedly had a quick test every day, but largely ignored other means such as face masks and social distance. It is possible that someone has been infected and is asymptomatic, has a negative test, and has since started to develop.

Extensive repetitive testing

To control the coronavirus, it is important to detect infectious presymptomatic and asymptomatic individuals. You can do this with a rapid test, but only if people are repeatedly screened according to a schedule. This is the same thing that happens in some professional and inter-university sports.

The idea is that by testing people early and often (perhaps as often as every day), you can catch infected people with rapid testing before spreading the coronavirus to others. But on a national scale, it’s a huge number of tests.

Researchers estimate that the United States needs to perform at least 20 million rapid tests per day to reduce infections. The 150 million rapid tests ordered by the government in late August were assigned to high-risk populations, but the population as a whole rarely covered a week. Also, keep in mind that you need to have all the logistics capabilities, compliance with frequent tests, and the infrastructure to respond quickly to results.

Targeted approach

The federal government is prioritizing the deployment of rapid testing in high-risk nursing homes, as the general public has not been tested fast enough to undergo repeated testing. The federal guidelines for the use of rapid testing in nursing homes are a good example of what a testing program looks like, but they also set the current challenges in using rapid testing.

If even one of the nursing homes tests positive, all staff and residents should be tested every 3-7 days until the facility is depleted of COVID-19 for 14 days. If there are no cases at the facility, all staff should be tested according to the county’s positive test rate. The higher the inspection rate, the more inspections are needed.

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However, nursing homes have problems with accuracy, staffing, and cost while using these tests and are once again at stake during the current surge. Rapid testing does help to catch many cases and should be used in these settings, but the larger problems that contribute to the spread in these settings cannot be overcome alone.

Rapid testing is effective in highly controlled settings where people are frequently tested and other mitigation measures are in place. Notice the success of the NBA Bubble as proof. However, in other environments where isolation, wearing masks, and increasing social distance were difficult or non-compliant (such as nursing homes and the White House), rapid testing kept the virus away.

Current testing capabilities are far from the hundreds of millions of tests required per week to protect the general public. To date, the promise of cheap and convenient COVID-19 testing, which is the only means of controlling disease transmission, has not been fulfilled.

This article has been republished from Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/rapid-covid-19-tests-can-be-useful-but-there-are-far-too-few-to-put-a-dent-in-the-pandemic-148429..